warning LEXUS SC400 1991 Service Repair Manual

CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diag. code detecting condition after diag. code is recorded.
(b) To check that the malfunction is corrected when the repair is completed co\
nfirming that diag. codeis no longer detected.
Malfunction: Open or Short in Sub±Oxygen Sensor

Initiate test mode (See page TR±12).
Start engine and warm up.
After engine is warmed up, let it idle for 3 min.
With the A/C ON and the transmission in D range (O/D OFF), drive at 40 ±\
60 mph (64±96
km/h) for 6 min.
After the driving in , stop the vehicle.
Once the vehicle is stopped, within the next minute apply acceleration w\
ith the throttle
fully open for 4 sec.
HINT: If a malfunction exists, the ºCHECKº engine warning light will light\
up after full acceleration for 4 sec.
NOTICE: If the conditions in this test are not strictly followed, detection of the\
malfunction will not be possible.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±83
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INSPECTION PROCEDURE
Check output condition of diag. code 43
Setting the test mode.
6. Turn ignition switch OFF.
7. Connect terminals TE2 and E1 of TDCL.
8. Turn ignition switch ON.(Don't start the engine)
9. Connect terminals TE1 and E1 of TDCL.
Check if code ª43º is output by the ªCHECKº en-
gine warning light.
Code ª43º is output.
Start the engine.
Check if the code ª43º disappear.
Code ª43º is not output.
Proceed to next circuit inspection shown on
matrix chart (See page
TR±39).
Check for open in harness and connector between engine (& ECT) ECU
and starter relay (See page IN±27)
Repair or replace harness or connector.
Check and replace engine (& ECT) ECU.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±97
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NGOK
OKNG
v
INSPECTION PROCEDURE
1Check output condition of diag. code 43.
C
OK
P
OK
C
Setting the test mode.
(2) Turn ignition switch OFF.
(2) Connect terminals TE2 and E1 of TDCL.
(2) Turn ignition switch ON.(Don't start the engine)
(2) Connect terminals TE1 and E1 of TDCL.
Check if code ª43º is output by the ªCHECKº engine
warning light.
Code ª43º is output.
Start the engine.
Check if the code ª43º disapears.
Code ª43º is not output.
Proceed to next circuit inspection shown on maxtric
chart (See page TR±35).
2Check for open in harness and connectors between engine & ECT ECU and st\
arter relay
(See page IN±27).
Repair or replace harness or connector.
Check and replace engine & ECT ECU.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±101
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CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diag. code detecting condition after diag. code is recorded.
(b) To check that the malfunction is corrected when the repair is completed c\
onfirming that diag. code is nolonger detected.
Malfunction: Open or Short in Knock Sensor

Start engine and warm up.
After engine is warmed up, let it idle for 3 min.
With the A/C ON, perform quick racing (5,000 rpm) three times.
(Rapidly depress the accelerator pedal and suddenly release it.)
HINT: If a malfunction exists, the ºCHECKº engine warning light will lig\
ht up when sudden racing is performed.
NOTICE: If the conditions in this test are not strictly followed, detection of t\
he malfunction will
not be possible.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±103
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CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS TROUBLE CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diag. trouble code detecting condition after diag. trouble co\
de is recorded.
(b) To check that the malfunction is corrected when the repair is completed co\
nfirming that diag. trouble codeis no longer detected.
Malfunction: Open in EGR gas temp. sensor circuit
Disconnect the EFI fuse (15 A) for 10 sec. or more, with IG switch OFF\
.
Initiate test mode (Connect terminal TE2 and E1 of check connector or TDCL with\
IG
switch OFF).
Start the engine and warm up.
After the engine is warmed up, let it idle for 3 min.
With the A/C ON and transmission in 5th gear (ECT in 3rd speed) drive at 5\
5 ~ 60 mph
(88 ~ 96 km/h) for 4 min or less.
HINT: If a malfunction exists, the ºCHECKº engine warning light will l\
ight up during step .
NOTICE: If the conditions in this test are not strictly followed, detection of \
the malfunction will not be possible.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±105
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CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSIS CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diag. code detecting condition after diag. code is recorded.
(b) To check that the malfunction is corrected when the repair is completed c\
onfirming that diag. code is nolonger detected.

Initiate test mode (See page TR±12).
Start engine and warm up.
After engine is warmed up, let it idle for 3 min.
With the A/C ON and transmission in D range (O/D OFF), drive at 40±\
70 mph for 4 min.
HINT: If a malfunction exists, the ºCHECKº engine warning light will light up at 1±4 min. of driving at 40±70 mph (64±112 km/h).
NOTICE: If the conditions in this test are not strictly followed, detection of the\
malfunction will not be possible.
Malfunction: Open in EGR gas temp. sensor circuit
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±109
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OKNG
OKNG
INSPECTION PROCEDURE
1Check output condition of diag. code 51.
C
OK
Hint
PSetting the test mode.
(2) Turn ignition switch OFF.
(2) Connect terminals TE2 and E1 and TDCL.
(2) Turn ignition switch ON.(For checking terminal A/C, start the engine.)
(2) Connect terminals TE1 and E1 of TDCL.
Check if code ª51º is output by the ªCHECKº engine
warning light.
*: Before the STA signal is input (ST is not ON), diagnostic code 43 is also output.
Diag. code 42 is output with vehicle speed 5 km/h (3
mph) or below
IDL1 .... Go to step 2 NSW ... Go to page TR±22.
A/C ..... Go to step 3
Proceed to next circuit inspection shown on
maxtrix chart (See page TR±35).
2Check throttle position sensor.
C
OK
PDisconnect throttle position sensor connector.
Measure resistance between terminals IDL1 and E2 of
throttle position sensor connector.
Adjust or replace throttle position sensor
See page FI±73).
Check and repair harness or connector between
engine & ECT ECU and throttle position sensor.
TR±120±
ENGINE TROUBLESHOOTING Circuit Inspection
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11 8
WIRELESS DOOR LOCK REMOTE CONTROL
7 6 10 542931
2 1
2
1E
11
1D
84
1J
1
1B
5
1I
64
1H
13
1D10 3E
7
3A 6
2
3
BY17
IP 1 20
BX1
2 BX1 11 BX1 8 BX19BX116 BX1 15 BX1 3
I8
I15
I7
B4 B7
9
10
6 3 6
3
BL IF IJ IP1
15
E KSW DSW D L1 LSWD1
UL1 LSWD2 LSWP
P±B
W±L
G± W
G±Y
L±W
W±B
W±B
W±B
W±B
W±B G±L
R±L
R
R
R
R±L
P±B
W±L L±W
G±W G±Y
G±W L±W G±Y
G±Y
G±W G±L
R±W Y
G±LY
W±B
G±L
R±W
R±W
W±B
W±B
W±B
W±B
W±B W±B
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
10A
DOME
+B
WIRE LES S DOOR LOCK E CU
WIRE LES S DOOR LOCK
MAIN SW
UNLOCK WARNING SW
[IGNITION SW]
DOOR OPEN
DE TE CTION SW LH
DOOR OPEN
DE TE CTION SW RH
INTEGRATION
RELAY DIODE
TO DOOR LOCK
AND UNLOCK SW LH
TO DOOR LOCK
AND UNLOCK SW RH
W8
I15
D10
D11
W7
2
1
4
6 IF2
15
IP 1
19
G±Y
G±W
I15
G±Y
TO DOOR LOCK
AND UNLOCK SW RH
IP1
8
G±Y
G±Y
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120
WIRELESS DOOR LOCK REMOTE CONTROL
DOOR LOCK CONTROL (LOCK AND UNLOCK) IS PERFORMED BY REMOTE CONTROL, WI\
THOUT THE IGNITION KEY INSERTED IN
THE DOOR KEY CYLINDER, USING LOW±POWER RADIO WAVES EMITTED BY A TRANSMITTER BUILT INTO IGNITION KEY.
1. WIRELESS DOOR LOCK OR UNLOCK NORMAL OPERATION
WITH THE WIRELESS DOOR LOCK MAIN SW ON, THE IGNITION KEY NOT INSERTED INTO THE IGNITION KEY CYLINDER (UNLOCK
WARNING SW OFF) AND ALL THE DOORS COMPLETELY CLOSED, WHEN THE SWITCH (TRANSMITTER) ON THE IGNITION KEY IS
PUSHED, THE WIRELESS DOOR LOCK ECU RECEIVES THE ELECTRICAL WAVES FROM THE IGNITION KEY (TRANSMITTER),
CAUSING IT TO OPERATE.
AS A RESULT, THE ECU JUDGES WHETHER THE DOOR IS LOCKED OR UNLOCKED BASED ON THE SIGNAL FROM THE DOOR LOCK
MOTOR, AND SENDS A SIGNAL TO THE DOOR LOCK ECU TO SWITCH THE CONDITION FROM LOCK TO UNLOCK OR VICE VERSA,
CAUSING THE DOOR LOCK MOTOR TO OPERATE (FOR THE CURRENT FLOW DURING LOCK AND UNLOCK REFER TO THE DOOR
LOCK CONTROL SYSTEM.)
2. AUTO LOCK OPERATION
AFTER PUSHING THE IGNITION KEY SWITCH (TRANSMITTER) TO UNLOCK ALL THE DOORS, IF A DOOR IS NOT OPENED WITHIN 30
SECONDS, ALL OF THE DOORS ARE AUTOMATICALLY LOCKED AGAIN.
3. WIRELESS DOOR LOCK STOP FUNCTION
IF A DOOR IS OPEN (DOOR COURTESY SW ON), A SIGNAL IS INPUT FROM THE DOOR OPEN COURTESY SW TO THE WIRELESS
DOOR LOCK ECU, STOPPING WIRELESS DOOR LOCK OR UNLOCK.
IF THE IGNITION KEY IS IN THE IGNITION KEY CYLINDER (UNLOCK WARNING SW ON), THE UNLOCK WARNING SWITCH INPUT A
SIGNAL TO THE WIRELESS DOOR LOCK ECU, STOPPING WIRELESS DOOR LOCK OR UNLOCK.
4. DOOR LOCK MOTOR PROTECTIVE FUNCTION
IF THE DOOR LOCK OR UNLOCK CONDITION DOES NOT CHANGE AFTER WIRELESS DOOR L\
OCK OR UNLOCK OPERATION, THE
DOOR LOCK ECU SENDS CURRENT TEN TIMES TO THE DOOR LOCK MOTOR. IF THE DOOR LOCK CONDITION STILL HAS NOT
CHANGED AS A RESULT THE WIRELESS DOOR LOCK ECU STOPS RECEPTION AND STOPS DOOR LOCK AND UNLOCK FUNCTION.
BY MANUALLY OPERATION THE DOOR LOCK OR UNLOCK, THE STOP CONDITION OF THE WIRELESS DOOR LOCK FUNCTION IS
RELEASED.
D10, D11 DOOR OPEN DETECTION SW LH, RH
3±6 : CLOSED WITH DOOR OPENED
I15 UNLOCK WARNING SW [IGNITION SW]
10±9 : CLOSED WITH IGNITION KEY IN CYLINDER
W 8 WIRELESS DOOR LOCK ECU
1±GROUND: APPROX. 12 VOLTS WITH WIRELESS DOOR LOCK MAIN SW ON
7±GROUND: ALWAYS CONTINUITY
10±GROUND: CONTINUITY WITH EACH DOOR OPENED
6±GROUND: CONTINUITY WITH IGNITION KEY IN CYLINDER
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
D1030I1529W 729
D1130T 929W 831
: RELAY BLOCKS
CODESEE PAGERELAY BLOCKS (RELAY BLOCK LOCATION)
219ENGINE COMPARTMENT LEFT
423LEFT KICK PANEL (J/B NO.1 LEFT)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1B20ENGINE ROOM MAIN WIRE
1D20FRONT DOOR LH WIRE
1E20INSTRUMENT PANEL WIRE
1H
1I20COWL WIRE1J20COWL WIRE
1K
3A22INSTRUMENT PANEL WIRE3E22INSTRUMENT PANEL WIRE
SYSTEM OUTLINE
SERVICE HINTS
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219
1E
2
IK1
6
I22
IHC
10
C
13 C 14 C 19 C20 C 16 C17 C18 C 6
412 97812
3A
5
3C
5
3F
6
L±R
L±R
V±R
RRR
V
V±W
B
R±Y W L±R
L±R
TRIP SW AND THEFT DETERRENT INDICATOR LIGHT 15A
CIG
TRIP METER
CIRCUIT
CLOCK SPEED
FROM POWER SOURCE SYSTEM
(
SEE PAGE 56 )
ENGINE OIL LEVEL
WARNING SW T15
C12 ,
3,C14
E6 COMBINATION METER
A
BC
OIL TEMP. OIL LEVEL
E20
W±B
ED C
15
A
1
B 2 AI39
SHORT CONNECTOR
,23
A
2 TO DOOR LOCK
CONTROL RELAY
L±R
W±B
BR
V±R
BR
BR
E2ACC
R
P
21
BR
BR
S22 BP
P
R
C1
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